Method for dual-polarized multiplexing and interference management in XL-MIMO using polarization characteristics

Abstract

A method performed by a dual-polarized receiver comprising an extra-large multiple-input multiple-output (XL-MIMO) antenna array (110) with antenna elements (111) each selectively operating in two orthogonal states for receiving signals from a dual-polarized transmitter in a joint radar-communication system, wherein the dual-polarized transmitter transmits dual polarized signal for radar sensing and communication, wherein the joint radar-communication system comprises a polarization medium between the dual polarized transmitter (200) and the dual polarized receiver (100) that introducing polarization interference and cross-polarization interference to the dual polarized signal. It is characterized by grouping antenna elements (111) based on polarization shift, co-polarization power level and cross polarization power level.

Description

[0001] DESCRIPTION

[0002] METHOD FOR DUAL-POLARIZED MULTIPLEXING AND INTERFERENCE MANAGEMENT IN XL-MIMO USING POLARIZATION CHARACTERISTICS

[0003] TECHNICAL FIELD

[0004] Invention relates to a method performed by a dual-polarized receiver comprising an extra-large multiple-input multiple-output (XL-MIMO) antenna array with antenna elements each selectively operating in two orthogonal states for receiving signals from a dual-polarized transmitter in a joint radar-communication system, wherein the dual-polarized transmitter transmits dual polarized signal for radar sensing and communication, wherein the joint radarcommunication system comprises a polarization medium between the dual polarized transmitter and the dual polarized receiver that introducing polarization interference and cross-polarization interference to the dual polarized signal.

[0005] PRIOR ART

[0006] Dual-polarized systems, where two distinct data streams (related to communication service, sensing service, or both) are transmitted simultaneously using orthogonal polarizations (e.g., horizontal and vertical), are highly efficient for spectral reuse. However, such systems are also vulnerable to polarization leakage or misalignment, causing interference between the streams.

[0007] In wireless communication, multiplexing different users or technologies has traditionally relied on exploiting various orthogonal domains, such as time, frequency, and code. While these domains have been extensively studied and utilized, one less-explored parameter of electromagnetic (EM) waves is the polarization domain. Polarization offers a unique opportunity for multiplexing, as it provides two orthogonal states: horizontal and vertical polarizations. These orthogonal polarization states can be effectively used to multiplex two users or services, enabling efficient resource utilization and enhanced system performance. However, the multiplexing gain in the polarization domain is significantly reduced in NLOS scenarios, where depolarization occurs due to reflections, scattering, and diffraction in the channel, leading to a loss of orthogonality and increased interference.

[0008] In [1], they introduce Polarization Division Multiple Access (PDMA) in NIoS in wide-band wireless channels. One limitation of the PDMA scheme is its reliance on collaborativepolarization adjustment, which requires both the transmitter and receiver to adaptively align their polarization states based on real-time channel conditions. This process can introduce additional complexity and latency, particularly in dynamic environments where rapid channel changes occur. Moreover, the effectiveness of polarization filtering detection depends heavily on accurate channel state information (CSI), which may not always be readily available or precisely estimated in NLoS scenarios. The method's reliance on adaptive processes and precise CSI can make it less practical in scenarios with limited computational resources or high mobility, such as in vehicular or loT networks. Additionally, the scheme may not fully mitigate cross-polarization interference (XPI) under extreme depolarization conditions, potentially limiting its scalability for dense multi-user deployments.

[0009] Similarly, in [2] the paper proposes a polarization-based multiplexing technique for spectrumefficient JRC, utilizing dual-polarization to transmit radar and communication signals on orthogonal polarization states. A key challenge it addresses is XPI caused by channel-induced depolarization in NLOS conditions. To mitigate this, the method employs polarization rotation matrix adjustments and cross-correlation techniques to separate co-polarized and crosspolarized components at the receiver. In this method still there is residual interference which can degrade the performance of both sensing and communication.

[0010] All the problems mentioned above have made it necessary to make an innovation in the relevant technical field as a result.

[0011] References

[0012] [1] S. -C. Kwon and G. L. Stuber, "Polarization Division Multiple Access on NLoS Wide-Band Wireless Fading Channels," in IEEE Transactions on Wireless Communications, vol. 13, no.

[0013] 7, pp. 3726-3737, July 2014.

[0014] [2] A. Naeem, M. Delamou, E. M. Amhoud and H. Arslan, "Polarization-Based Multiplexing: Enabling Spectrum Efficient Joint Radar and Communication," in IEEE Wireless Communications Letters, vol. 13, no. 5, pp. 1414-1418, May 2024.

[0015] BRIEF DESCRIPTION OF THE INVENTION

[0016] The present invention relates to a method to eliminate the above-mentioned disadvantages and bring new advantages to the relevant technical field.An object of the invention is to reduce inter-stream interference and increase spectral efficiency in extra-large multiple input multiple output (XL-MIMO) systems.

[0017] To achieve all the objects mentioned above and that will emerge from the following detailed description, the present invention relates to a method performed by a dual-polarized receiver comprising an extra-large multiple-input multiple-output (XL-MIMO) antenna array with antenna elements each selectively operating in two orthogonal states for receiving signals from a dual-polarized transmitter in a joint radar-communication system, wherein the dual-polarized transmitter transmits dual polarized signal for radar sensing and communication, wherein the joint radar-communication system comprises a polarization medium between the dual polarized transmitter and the dual polarized receiver that introducing polarization interference and cross-polarization interference to the dual polarized signal. Accordingly, characterized in that comprising the steps of: receiving the dual polarized signal from dual-polarized transmitter; measuring polarization shifts of antenna elements where each antenna element is preallocated to operate in one of the states; measuring cross-polarized power and co-polarized power of each antenna element; grouping antenna elements having approximately 0 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a radar sub-array for performing radar sensing; grouping antenna elements having approximately 90 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a communication sub-array for performing communication; controlling antenna elements based on groups for radar sensing or communication. Thus, challenges of cross-polarization interference caused by channel depolarization are addressed by exploiting the unique polarization shifts experienced by each antenna element in XL-MIMO systems. By leveraging these per-element polarization variations, the system can dynamically adjust and compensate for the loss of orthogonality, ensuring robust multiplexing performance even in NLOS environments.

[0018] The invention addresses the vulnerability to polarization leakage or misalignment, causing interference between the streams by dynamically aligning polarization angles and adjusting power levels across antenna elements in real-time. This approach effectively isolates the data streams, reducing cross-polarization interference, maintaining signal clarity, and ensuring high spectral efficiency even in environments with significant multipath and reflection effects. Thus, with dual-polarized multiplexing, this invention allows networks to double their data-carrying capacity by transmitting two data streams per antenna element. The technical advantage of using polarization control to mitigate inter-stream interference means that XL-MIMO networks can maximize their spectral efficiency, which is crucial for supporting high data rates andmassive user connections in 5G and 6G applications. The invention’s reliance on polarization for interference management provides a scalable solution that can be adapted to different XL-MIMO configurations and diverse environmental conditions. Its technical approach is compatible with evolving wireless standards and can be applied in various frequency bands, making it highly relevant for the flexible and adaptive requirements of future wireless networks.

[0019] A possible embodiment of the invention is characterized in that comprising the steps of: comparing co-polarization power and cross-polarization power of each antenna element; excluding the antenna elements having cross-polarization power higher than the copolarization power by greater than a predetermined margin from radar sub-array and communication sub-array groups.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a drawing illustrating top schematic view of the system.

[0022] REFERENCE NUMBERS GIVEN IN THE FIGURE

[0023] 100 Dual polarized receiver

[0024] 110 XL-MIMO antenna array

[0025] 111 Antenna element

[0026] 200 Dual polarized transmitter

[0027] 300 Visibility region

[0028] 400 Depolarization medium

[0029] DETAILED DESCRIPTION OF THE INVENTION

[0030] In this detailed description, the subject matter is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

[0031] Invention is a method performed by a dual polarized receiver (100) of a joint radar communication system.

[0032] In such systems, radar capabilities involve detecting objects, determining their distance, speed, and direction, and tracking their movement. Communication capabilities involve transmitting data between devices or systems for information exchange. By combining thesefunctions, joint radar-communication systems serves dual purposes, such as providing situational awareness while enabling data transmission in real-time.

[0033] Referring to figure 1, the joint radar communication system comprises a dual polarized transmitter (200). Dual polarized transmitter (200) transmits radar and communication signals in orthogonal polarizations. For instance, dual polarize transmitter transmits vertically and horizontally polarized signals. For instance, vertically polarized signals are used for radar and horizontally polarized signals are used for communication.

[0034] Dual polarized receiver (100) comprises extra large-multiple input multiple output antenna array (110) (XL-MIMO antenna array) comprising antenna elements (111). Antenna elements (111) are configured to operate in two orthogonal polarization states. Said polarization states may be vertical and horizontal. For instance, vertical polarization is used for radar and horizontal polarization is used for communication.

[0035] Dual polarized receivers (100) are well known in the art. For instance, the receiver may further comprise a signal processing unit configured to process the received signals by decomposing them into their respective polarization components and extracting communication and radar information. The receiver may comprise a polarization control module configured to control the polarization states of the antenna elements (111).

[0036] The dual polarized receiver (100) is configured to analyze each antenna elements (111) signal. The dual polarized receiver (100) is configured to measure polarization signal of each antenna element (111). Further, the dual polarized receiver (100) is configured to measure cross- polarization power and co-polarization power of received signal of each antenna element (111).

[0037] Each antenna element (111) experiences a unique polarization shift, modeled as:

[0038]

[0039] where:

[0040] a0: Initial polarization angle.

[0041] A: Signal wavelength.

[0042]

[0043] > ro:Distance differential for element / , where d is the spacing between antennas, and r0is the reference distance.Received Signal Model is as follows: The received signal at each antenna element (111) / is:

[0044] Vi co,i co T -cross, i cross T 1 /

[0045] where:

[0046] hcoi : Channel gain for the co-polarized component.

[0047] hcross i:Channel gain for the cross-polarized (interference) component.

[0048] xcoand xcross: Co-polarized and cross-polarized signals, respectively.

[0049] ni : Additive noise at element ill.

[0050] The system further comprises a depolarization medium (400) between the dual polarized receiver (100) and the dual polarized transmitter (200). Signals propagate through the medium introducing polarization leakage, leading to interference between the orthogonal polarization states.

[0051] The method comprises below steps realized by the dual polarized receiver (100):

[0052] - receiving the dual polarized signal from dual-polarized transmitter;

[0053] - measuring polarization shifts of antenna elements (111) where each antenna element (111) is pre-allocated to operate in one of the states;

[0054] - measuring cross-polarized power and co-polarized power of each antenna element (111); - grouping antenna elements (111) having approximately 0 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a radar sub-array for performing radar sensing;

[0055] - grouping antenna elements (111) having approximately 90 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a communication subarray for performing communication;

[0056] - controlling antenna elements (111) based on groups for radar sensing or communication.

[0057] In a possible embodiment, the method further comprises below steps:

[0058] - comparing co-polarization power and cross-polarization power of each antenna element (111);

[0059] - excluding the antenna elements (111) having cross-polarization power higher than the copolarization power by greater than a predetermined margin from radar sub-array and communication sub-array groups.The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.

Claims

CLAIMS1. A method performed by a dual-polarized receiver comprising an extra-large multipleinput multiple-output (XL-MIMO) antenna array (110) with antenna elements (111) each selectively operating in two orthogonal states for receiving signals from a dual-polarized transmitter in a joint radar-communication system, wherein the dual-polarized transmitter transmits dual polarized signal for radar sensing and communication, wherein the joint radar-communication system comprises a polarization medium between the dual polarized transmitter (200) and the dual polarized receiver (100) that introducing polarization interference and cross-polarization interference to the dual polarized signal characterized in that comprising the steps of:receiving the dual polarized signal from dual-polarized transmitter; measuring polarization shifts of antenna elements (111) where each antenna element (111 ) is pre-allocated to operate in one of the states;measuring cross-polarized power and co-polarized power of each antenna element (111);grouping antenna elements (111) having approximately 0 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a radar sub-array for performing radar sensing;grouping antenna elements (111) having approximately 90 degrees polarization shift and having co-polarized power higher than a predetermined threshold into a communication sub-array for performing communication;controlling antenna elements (111) based on groups for radar sensing or communication.

2. The method according to claim 1 , characterized in thatcomparing co-polarization power and cross-polarization power of each antenna element (111);excluding the antenna elements (111) having cross-polarization power higher than the co-polarization power by greater than a predetermined margin from radar subarray and communication sub-array groups.

3. A dual-polarized receiver comprising an extra-large multiple-input multiple-output (XL- MIMO) antenna array (110) with antenna elements (111) each selectively operating in two orthogonal states for receiving signals from a dual-polarized transmitter in a joint radar-communication system, wherein the dual-polarized transmitter transmits dualpolarized signal for radar sensing and communication, wherein the joint radarcommunication system comprises a polarization medium between the dual polarized transmitter (200) and the dual polarized receiver (100) that introducing polarization interference and cross-polarization interference to the dual polarized signal characterized in that the dual-polarized receiver is configured to perform one of the methods of claim 1 or 2.

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